Centrifugal casting processes and apparatus for casting true paraboloidal convex surface patterns



2,719,327 CENTRIFUGAL CASTING PROCESSES AND APPARATUS FOR CASTING Oct.4, 1955 B. J. PIQUEI TRUE PARABOLDIDAL CONVEX SURFACE PATTERNS FiledMqrvh 19 1951 Fie.2

INVENTOR United States PatentO My invention relates to improvements incentrifugal casting processes and apparatus for casting trueparaboloidal convex surface patterns. It has been designed moreparticularly as a device for making feasible the construction of partsthat are combined in my invention described and claimed inthe continuingapplication Serial Number 450,982 (filed August 19, 1954, for NegativePattern and Hollow Mold for Casting Compound Reflector Members, which isa device for making commercially practicable thejadaptation 'of thecomplementary parts combined in my invention disclosed and claimed inthe United States Letters Patent Number 2501,1 issued March 21, 1950 forElectric-Light Projecting Reflector.

It is known that the best concave surface produced with extreme accuracyis the paraboloid of revolution, because when a liquid body is containedin a receptacle which rotates uniformly, the surface of the liquid takesthe form of an accurate paraboloid. The natural surface of liquids in anabsolute or relative state of repose are extremely accurate. When thisliquid consists of a solid in fused condition, and is cooled whilecontinuing at the same angular velocity, the liquid body will solidify,

conserving the paraboloidal surface.

When two bodies having different physical conditions, referring to theirspecific weights and fusion points, are contained in fused conditionwithin a receptacle, the

heavier liquid will be under the lighter liquid. When these liquids arein absolute or relative state of repose, the liquid joint surface willhave equal shape than the top liquid surface. When these two liquids arecontained in a receptacle which rotates uniformly, the top liquidsurface and the liquid joint surface take equal forms of accurateparaboloid. If the receptacle continue at the same angular velocitywhile the liquids are cooling, these liquid bodies will solidifycomprising paraboloidal surfaces accurately formed.

One of the advantages of such casting process is to produce negativepattern having true paraboloidal convex surface.

As wrought concave and convex surfaces are not as accurate as is desiredfor patterns, one of the objects of my improvement is to form negativepatterns having true half paraboloidal convex surfaces.

A further object of my improvement is the provision of an apparatuscomprising a receptacle that rotates uniformly having means for holdingdeterminate quantities of two melted materials, according to the angularvelocity applied to said receptacle. These melted materials havingditferent physical conditions with each other, referring their specificweights and fusion points, will form separable composite casting.

Another object of my improvement in connection with such centrifugalcasting apparatus, is the process with two melted materials for makingcouple of half paraboloidal convex patterns, which process comprises toregulate alternately the amount of said two melted materials to beconformed in said centrifugal casting apparatus. One of said meltedmaterial will be adjusted as part of mold in connection with saidapparatus and the other one melted material will be conformed foreasting to obtain said couple of half paraboloidal'convex patterns.

Another object of my improvement is to provide'means in a centrifugalcasting apparatus for making with two melted materials couple of halfpatterns having an inner plane border limiting half convexparaboloid anda bevel border of uniform thickness at their peripheries. The apparatusmay be so operated in a centrifugal casting process that each couple ofhalf patterns cast in the apparatus will have a different convexcurvature from every other couple cast in the same apparatus and havingthe same thickness of bevel border at their peripheries.

Other objects and advantages of my invention will appear from thefollowing description with reference to the accompanying drawings, inwhich: Fig. l is a vertical sectional view of an appropriate apparatusfor centrifugal casting, showing the improvements; Fig. 2 is a sectionalview of a hollow mold showing the object attained with this invention;and Fig. 3 is a sectional View through the line 33 of Fig. 1. Similarnumerals refer to the same or similar parts through the figures.

Referring to Fig. l and Fig. 3, my invention comprises:

An apparatus for centrifugal casting comprisinga receptacle A having acurved base 1 with the inner side forming a rippled paraboloidal surface2. Said receptacle A is provided with a cylindrical end 4 having aconical edge at the periphery thereof.

A thin blade 9 having a paraboloidal border is fitted and attached byits border on the inner paraboloidal rippled surface 2 of saidreceptacle A.

A rotor axle 3 attached to the receptacle A, is placed vertically in amachine not shown in the drawings, which rotates uniformly together withthe receptacle A around its symmetrical axis.

A melted material 10 is put within the receptacle A to be adapted aspart of mold, which will be adjusted in connection with said receptacleA according to the angular velocity in the process of centrifugalcasting.

A conical ring 5 having an inner sharp edge 6, is as sembled with saidcylindrical end 4 at theperiphery of receptacle A, it being fitted bymeans of a ring flange 7.

Another melted material 11, having lighter specific weight and higherfusion point than the first one, is put within the receptacle A forcasting couple of half paraboloidal convex patterns 11-11 upon saidfirst melted material 10.

The cylindrical end 4 with its conical edge is adapted at the peripheryof receptacle A to regulate the amount of the first melted material 10.The conical ring 5 with its inner sharp edge 6 is adapted upon thecylindrical end 4 of receptacle A to regulate the amount of the secondmelted material 11 and to form a bevel border 14 at the peripheries ofcasting patterns. And, the thin blade 9 is adapted in the receptacle Ato disjoint halves of said casting pattern 11 through a plane holdingthe axis of paraboloidal surface 12, and for forming an inner planeborder 9' in the casting pattern 11 limiting half convex paraboloid 12and thus obtaining a couple of half patterns 1111.

An annular pan 8 is located separately surrounding the rotor receptacleA.

The process with two melted materials for making couple of halfparaboloidal convex patterns, in connection with this centrifugalcasting apparatus, is as follows:

When the receptacle A, without the conical ring 5, rotates with apredeterminate velocity having within it the melted material 10, thematerial will flow upward by centrifugal force and its top surface takesthe paraboloidal shape 12 with a concave curvature according to theangular velocity applied to said receptacle A. This happens after theexcess of liquid mass 10 is spilled out of the cylindrical end 4 bycentrifugal force to the annular pan 8, and an appropriate quantity ofsaid melted material 1 is retained by said cylindrical end 4 to beadjusted as part of mold in connection with said receptacle A.

After this, fitting the conical ring 5 upon the cylindrical end 4 ofreceptacle A, and then, when said receptacle A rotates with the samepredeterminate velocity, the other melted material 11 from which halfparaboloidal convex patterns will be formed, is put within thereceptacle A and upon the first material 10, whence, the second meltedmaterial 11 flow upward by centrifugal force, the excess of thismaterial 11 will be spilled out from inner sharp edge 6 of conical ring5 to the annular pan 8, and an appropriate quantity of said material 11is retained by said conical ring 5 to be conformed for casting. Theliquid joint surface 12 will be a predeterminate true paraboloidalsurface as same as the top liquid surface 12'. Furthermore, the thinblade 9 will form in the half patterns an inner plane border 9' limitinghalf convex paraboloid 12, and the conical ring 5 will form a bevelborder 14 of uniform thickness at the peripheries of half patterns 11.

When the materials 10 and 11 are cooled by lowering their temperaturebetween the temperatures of fusion points of both materials 10 and 11,the material 11 having higher fusion point than the material 10, will besolidified, and the material 10 will continue melted, forming separablecomposite casting. In this condition, after take out the conical ring 5,the solidified material 11 may be taken out by a suction cup.

Making another couple of half patterns 1111', by

distinct angular velocity of receptacle A than that of the firstpatterns1111, it after have been corrected the quantity of the first material 10according to the angular velocity applied to the receptacle A inaccordance with the curvature required in such couple of half patterns11'11.

Each different couple of half patterns 11-11 and 11'11, will havedifferent paraboloidal convex curvatures 12 and 13, and with the sameuniform thickness of bevel border 14 at their peripheries, it shaped bythe conical ring 5, and an inner plane border 9 limiting halfparaboloids 12 and 13, it shaped by the thin blade 9.

Two different half patterns 11 and 11, taken from two different couplesof half patterns, may be joined and welded together through their innerplane border 9 as is shown in Fig. 2, to constitute a negative patternhaving half convex paraboloids 12 and 13 with different convex curvatureand displaced from each other along the paraboloidal axis but theirperipherical bevel border 14 coinciding in ring section.

This negative pattern 1111', which comprises true half paraboloidalconvex surfaces 12-13, may be used as compound surface pattern inpressing apparatus or in hollow mold as is shown in Fig. 2.

A plate base having a bevel ring support 15 to adjust the compoundnegative pattern 1111' throughout its peripherical bevel border 14. Anda cover member 16 having an inner paraboloidal concave surface 17, isadapted on said bevel ring support 15, closing said negative pattern1111 in a hollow mold 19. The cover member 16 have a hole 18communicating the hollow mold 19 with the exterior. 1

This hollow mold 19, Fig. 2, is formed among the concave paraboloidalsurface 17 and both half convex paraboloids 12 and 13 having differentcurvature with each other, and ending the hollow mold 19 on the bevelring support 15. The casting is made through the hole 18 into the hollowmold 19 for making paraboloidal reflectors comprising half paraboloidalconcave surfaces 1213 with different concave curvature and displacedfrom each other along the paraboloidal axis, and having theirperipheries coinciding in conical ring section.

I claim:

An apparatus for centrifugal casting comprising a receptacle having aninner paraboloidal rippled surface and being adapted to rotate uniformlyaround its symmetrical axis, the said receptacle being provided with acylindrical end at the periphery thereof, a conical ring having an innersharp edge assembled with said cylindrical end and a thin blade having aparaboloidal border fitted and attached on the inner paraboloidalrippled surface of said receptacle.

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